Question

我的收藏品看起来像这样。

  var list = [{id:'12345', sequence:null}, {id:'12346', sequence:null}, {id:'12347', sequence:null}, {id:'12348', sequence:1}, {id:'12348', sequence:2}, {id:'12349', sequence:1}, {id:'12349', sequence:1}];

我正在尝试获取一个唯一的列表，以便具有相同id和序列的对象只返回其中一个对象（我们在这里有2个 - {id：'12349'，序列：1}）

我的代码

  var uniqueList = _.uniq(list, function(obj) {
    return obj.id && obj.sequence;
  });

我们可以像这样使用lodash uniq吗？解决这个问题的方法是什么？

Answer 1

您可以使用uniqBy()来计算生成列表的标准，其中iteratee回调返回集合中每个项目的id和sequence的连接值。当您只希望将特定属性作为唯一性标准时，下面的解决方案非常有用，尤其是当您的集合中的每个对象不仅具有id和sequence属性时。

var result = _.uniqBy(list, v => [v.id, v.sequence].join());

var list = [{
  id: '12345',
  sequence: null
}, {
  id: '12346',
  sequence: null
}, {
  id: '12347',
  sequence: null
}, {
  id: '12348',
  sequence: 1
}, {
  id: '12348',
  sequence: 2
}, {
  id: '12349',
  sequence: 1
}, {
  id: '12349',
  sequence: 1
}, {
  id: '123490',
  sequence: 1,
  extra: 1
}, {
  id: '123490',
  sequence: 1,
  extra: 2
}];

var result = _(list)
  .uniqBy(v => [v.id, v.sequence].join())
  .value();

document.write('<pre>' + JSON.stringify(result, 0, 4) + '</pre>');

<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.12.0/lodash.js"></script>

或者，如果您的属性包含要用作条件的非原始值（对象或数组），那么您仍然可以使用上面的解决方案，但是要加入值数组，您必须使用{{3} }

var result = _.uniqBy(list, v => JSON.stringify([v.id, v.sequence]));

var list = [{
  id: '12345',
  sequence: null
}, {
  id: '12346',
  sequence: null
}, {
  id: '12347',
  sequence: null
}, {
  id: '12348',
  sequence: 1
}, {
  id: '12348',
  sequence: 2
}, {
  id: '12349',
  sequence: 1
}, {
  id: '12349',
  sequence: 1
}, {
  id: '123490',
  sequence: 1,
  extra: 1
}, {
  id: '123490',
  sequence: 1,
  extra: 2
}];

var result = _.uniqBy(list, v => JSON.stringify([v.id, v.sequence]));

document.write('<pre>' + JSON.stringify(result, 0, 4) + '</pre>');

<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.12.0/lodash.js"></script>

<强>更新

对于lodash3解决方案，对于具有原始值的属性，您仍然可以使用JSON.stringify()在第一个解决方案中使用该模式。

var result = _.uniq(list, v => [v.id, v.sequence].join());

var list = [{
  id: '12345',
  sequence: null
}, {
  id: '12346',
  sequence: null
}, {
  id: '12347',
  sequence: null
}, {
  id: '12348',
  sequence: 1
}, {
  id: '12348',
  sequence: 2
}, {
  id: '12349',
  sequence: 1
}, {
  id: '12349',
  sequence: 1
}, {
  id: '123490',
  sequence: 1,
  extra: 1
}, {
  id: '123490',
  sequence: 1,
  extra: 2
}];

var result = _.uniq(list, v => [v.id, v.sequence].join());

document.write('<pre>' + JSON.stringify(result, 0, 4) + '</pre>');

<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/3.10.1/lodash.js"></script>

对于非原始属性，您仍然可以使用上面的第二个示例uniq()

var result = _.uniq(list, v => JSON.stringify([v.id, v.sequence]));

var list = [{
  id: '12345',
  sequence: null
}, {
  id: '12346',
  sequence: null
}, {
  id: '12347',
  sequence: null
}, {
  id: '12348',
  sequence: 1
}, {
  id: '12348',
  sequence: 2
}, {
  id: '12349',
  sequence: 1
}, {
  id: '12349',
  sequence: 1
}, {
  id: '123490',
  sequence: 1,
  extra: 1
}, {
  id: '123490',
  sequence: 1,
  extra: 2
}];

var result = _.uniq(list, v => JSON.stringify([v.id, v.sequence]));

document.write('<pre>' + JSON.stringify(result, 0, 4) + '</pre>');

<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/3.10.1/lodash.js"></script>

Answer 2

否。使用uniqWith。并使用与isEqual相同的签名编写正确的比较器。

Answer 3

您可以使用uniqWith

此方法与_.uniq类似，只是它接受比较器，该比较器被调用以比较数组的元素。使用两个参数调用比较器：（arrVal，othVal）。

和isEqual

在两个值之间执行深度比较，以确定它们是否相同。

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    xmlns:pew="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:orientation="vertical"
        android:weightSum="1.0">

        <LinearLayout
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:orientation="horizontal"
            android:weightSum="1.0"
            android:layout_weight=".25">

            <ImageView
                android:layout_height="wrap_content"
                android:layout_weight=".5"
                android:layout_width="0dip"
                android:src="@drawable/img"
                android:scaleType="centerCrop"/>

            <RelativeLayout
                android:layout_height="match_parent"
                android:layout_weight=".5"
                android:layout_width="0dip"
                android:background="@color/mainBlue">
                <TextView
                    android:layout_width="match_parent"
                    android:layout_height="wrap_content"
                    android:text="Sezione 1"
                    android:gravity="left"
                    android:layout_centerInParent="true"
                    android:textColor="@color/white"
                    android:textSize="20sp"
                    android:textStyle="bold"
                    android:layout_margin="10dp"/>
            </RelativeLayout>

        </LinearLayout>

        <LinearLayout
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:orientation="horizontal"
            android:weightSum="1.0"
            android:layout_weight=".25">

            <RelativeLayout
                android:layout_height="match_parent"
                android:layout_weight=".5"
                android:layout_width="0dip"
                android:background="@color/mainBlue">
                <TextView
                    android:layout_width="match_parent"
                    android:layout_height="wrap_content"
                    android:text="Sezione 2"
                    android:gravity="left"
                    android:layout_centerInParent="true"
                    android:textColor="@color/white"
                    android:textSize="20sp"
                    android:textStyle="bold"
                    android:layout_margin="10dp"/>
            </RelativeLayout>

            <ImageView
                android:layout_height="wrap_content"
                android:layout_weight=".5"
                android:layout_width="0dip"
                android:src="@drawable/img"
                android:scaleType="centerCrop"/>

        </LinearLayout>

        <LinearLayout
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:orientation="horizontal"
            android:weightSum="1.0"
            android:layout_weight=".25">

            <ImageView
                android:layout_height="wrap_content"
                android:layout_weight=".5"
                android:layout_width="0dip"
                android:src="@drawable/img"
                android:scaleType="centerCrop"/>

            <RelativeLayout
                android:layout_height="match_parent"
                android:layout_weight=".5"
                android:layout_width="0dip"
                android:background="@color/mainBlue">
                <TextView
                    android:layout_width="match_parent"
                    android:layout_height="wrap_content"
                    android:text="Sezione 1"
                    android:gravity="left"
                    android:layout_centerInParent="true"
                    android:textColor="@color/white"
                    android:textSize="20sp"
                    android:textStyle="bold"
                    android:layout_margin="10dp"/>
            </RelativeLayout>
        </LinearLayout>

        <LinearLayout
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:orientation="horizontal"
            android:weightSum="1.0"
            android:layout_weight=".25">

            <RelativeLayout
                android:layout_height="match_parent"
                android:layout_weight=".5"
                android:layout_width="0dip"
                android:background="@color/white">
                <ImageView
                    android:layout_width="30dp"
                    android:layout_height="30dp"
                    android:src="@drawable/icon_news"
                    android:scaleType="centerInside"
                    android:layout_centerHorizontal="true"
                    android:layout_above="@+id/newsTextView"
                    />
                <TextView
                    android:id="@+id/newsTextView"
                    android:layout_width="match_parent"
                    android:layout_height="wrap_content"
                    android:text="News"
                    android:gravity="center_horizontal"
                    android:layout_centerInParent="true"
                    android:textColor="@color/mainBlue"
                    android:textSize="20sp"
                    android:textStyle="bold"
                    android:layout_margin="10dp"/>
            </RelativeLayout>

            <RelativeLayout
                android:layout_height="match_parent"
                android:layout_weight=".5"
                android:layout_width="0dip"
                android:background="@color/white">
                <ImageView
                    android:layout_width="30dp"
                    android:layout_height="30dp"
                    android:src="@drawable/icon_contacts"
                    android:scaleType="centerInside"
                    android:layout_centerHorizontal="true"
                    android:layout_above="@+id/contactTextView"
                    />
                <TextView
                    android:id="@+id/contactTextView"
                    android:layout_width="match_parent"
                    android:layout_height="wrap_content"
                    android:text="Contatti"
                    android:gravity="center_horizontal"
                    android:layout_centerInParent="true"
                    android:textColor="@color/mainBlue"
                    android:textSize="20sp"
                    android:textStyle="bold"
                    android:layout_margin="10dp"/>
            </RelativeLayout>

        </LinearLayout>

    </LinearLayout>
</RelativeLayout>

javascript - lodash - 基于多个属性创建唯一列表

3 个答案: